The stylus converts the shape of grooves to electronic signal. Because the stylus is in physical contact, friction noise is generated. The more weight pressing down on the stylus, the louder the noise is. Adjusting for lightest tone arm weight without skipping is important.
Dust and static contribute noise. Sound Forge "hears" quiet spots of a certain duration before leaving a track marker. Using brushes for removing dust from stylus and LP improves noise performance. Often LP brushes will allow the addition of a liquid antistatic treatment.
Two-pronged plugs with an additional wire for grounding are often found on turntables. Be sure this is connected to a ground source to prevent hum.
It is simple to add a track marker using the software. The wave display shows where current markers are. Simply right click where needed and select "Add Marker" from the pop-up window.